ecotox consult - Dr. Michael Meller - ecotoxicological consulting service

Abstract

The toxicity of lindane, hexachlorobenzene, and copper sulfate to Tubifex tubifex and Limnodrilus hoffmeisteri was determined using an easily applicable and standardizable 72-h short-term test system. It was designed for the quick assessment of sublethal and lethal effects of sediment-associated chemicals on the worms. An artificial sediment based on the Artificial Soil according to OECD Guideline No. 207 was used as test medium. The data confirm the common view that oligochaetes are highly tolerant of lethal effects. However, sublethal effects were detected at considerably lower concentrations than found for lethal effects. The EC₅₀ values for autotomy (172 mg/kg dry wt sediment) and sediment avoidance (217 mg/kg) for T. tubifex exposed to lindane-contaminated sediment were, for example, more than five times lower than the LC₅₀ value (>1000 mg/kg). The no-observed-effect concentration (NOEC) for reworking activity (8 mg/kg) was more than 125 times lower than the LC₅₀. Tubificids thus turned out to represent useful test organisms for the assessment of the ecotoxicological hazard potential of chemicals in the sediment compartment, because the sublethal effects not only affect the individual, but can influence the population levels and, consequently, the composition of the benthic community.